Flame retardant electrical wire

Abstract

An electrical wire comprising conductor and a covering disposed over the conductor. The covering comprises a thermoplastic composition. The thermoplastic composition comprises a poly(arylene ether); a polypropylene, a block copolymer; and an organophosphate ester. The sum of weighted average aryl alkylene content of the block copolymer and the amount of organophosphate ester is greater than or equal to 46.5.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Application Ser. No. 60 / 637,406, filed on Dec. 17, 2004, which is incorporated in its entirety by reference herein.BACKGROUND OF INVENTION [0002] Automotive electrical wire located under the hood in the engine compartment has traditionally been insulated with a single layer of high temperature insulation that is disposed over an uncoated copper conductor. Thermoplastic polyesters, cross linked polyethylene and halogenated resins such as fluoropolymers, polyvinyl chloride have long filled the need for the high temperature insulation needed in this challenging environment that requires not only heat resistance, chemical resistance, flame retardance, and flexibility. [0003] Thermoplastic polyester insulation layers have outstanding resistance to gas and oil, are mechanically tough and resistant copper catalyzed degradation but can fail prematurely due to hydrolysis. The insulation layers...

AI Technical Summary

Benefits of technology

[0009] In addition, flame retardance becomes increasingly difficult as the insulation wall thickness d

Problems solved by technology

Thermoplastic polyester insulation layers have outstanding resistance to gas and oil, are mechanically tough and resistant copper catalyzed degradation but can fail prematurely due to hydrolysis.

The insulation layers in thermoplastic polyester insulated electrical wires have also been found to crack when exposed to hot salty water and have failed when subjected to humidity temperature cycling.

Cross linked polyethylene has largely been successful in providing high temperature insulation but this success may be difficult to sustain as the requirements for automotive electrical wire evolve.

The reductions in insulation wall thickness pose difficulties when using crosslinked polyethylene.

For crosslinked polyethylene the thinner insulation layer thickness result in shorter thermal life, when aged at oven temperatures between 150° C. and 180° C. This limits their thermal rating.

But with a similar electrical wire having a crosslinked polyethylene insulation layer with a 0.25 millimeter wall thickness, the insulation layer becomes brittle after being exposed to 150° C. for 3,000 hours.

The deleterious effects created by these extremely thin wall requirements have been attributed to copper catalyzed degradation, which is widely recognized as a problem in the industry.

It is possible to coat the copper core with, e.g., tin, in order to prevent the copper from contacting the crosslinked polyethylene but the additional cost of the coating material and the coating process are expensive.

However, manufacture of bilayer and trilayer insulation materials is complex, requires increased capital expenditure and the multi layer material presents new issues of inter layer adhesion.

In addition, flame retardance becomes increasingly difficult as the insulation wall thickness decreases, due, at least in part, to the insulation layer having a larger surface area to volume ratio.

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